(1) Field of the Invention
This invention relates to conductive carpet and, more particularly, to conductive carpet molded of conductive loaded resin-based materials comprising micron conductive powders, micron conductive fibers, or a combination thereof, substantially homogenized within a base resin when molded. This manufacturing process yields a conductive part or material usable within the EMF or electronic spectrum(s).
(2) Description of the Prior Art
In an Electrostatic Discharge (ESD) controlled environment, the static generated by walking on the floor must typically be less than 0.2 kV (200 volts). Carpeting that is used in ESD controlled areas, such as those involved in electronic-component assembly or where electronic components and/or circuit boards are routinely handled, must be conductive to dissipate static electricity induced by movement of people and equipment within the area. Companies such as UltraStat 2000 Inc., Colorado City, Colo. 81019; Julie Industries, Wilmington, Mass. 01887; Shakespeare Monofilaments and Specialty Polymers, Columbia, S.C. 29223; and Tarkett SAS, Nanterre Cedex, France manufacture carpeting containing electrically conductive fibers and material for the dissipation of the electrostatic discharges.
A related type of carpet is “intelligent carpeting” which integrates sensors and conductive circuits into a carpet covering. Infineon Technologies AG, Muenchen, Germany Munich has developed a way to make large textile surfaces, such as carpeting or tent cloth, “intelligent”. This technology innovation may lead to new products for the monitoring of buildings, the structural control of buildings of all kinds and for use in the advertising industry. A self-organizing network of robust chips is woven into fabric to enable the fabric to monitor temperatures, pressures or vibrations as required. In addition to the sensor functionality, the fabric can be equipped with tiny light-emitting diodes (LEDs) to provide directional guidance or serve as advertising material. In this manner, the “intelligent” fabric could be used as a motion sensor or fire alarm or to control burglar alarm and air-conditioning systems. To provide communication and connections between the chips embedded within the fabric, the fabric must contain electrical conductors for transmission of electrical power and for communication of signals.
Several prior art inventions relate to conductive carpeting. U.S. Pat. No. 4,336,028 to Tomibe et al teaches a method to make electrically conductive carpet fibers where acrylic fibers are treated in a copper ion bath. U.S. Pat. No. 4,388,370 to Ellis et al teaches a method to make electrically conductive piles and fibers by incorporating carbon black. U.S. Pat. No. 4,999,231 to Fowler teaches a method and a product to enhance electrical conductivity of films containing conductive carbon black. U.S. Pat. No. 4,228,194 to Meeder teaches an electrically conductive article and method of manufacturing the same. Electrically conductive fibers coated with lubricating oil and dispersed in an insulating material such as polyurethane. U.S. Pat. No. 4,309,479 to Naruse et al teaches conductive composite filaments comprising a synthetic thermoplastic fiber-forming polymer and carbon black. U.S. Pat. No. 4,913,952 to Fowler teaches carpet composites with improved static electricity characteristics and having a backing layer comprising a thermoplastic resin material with carbon black and carbon fibers mixed therein. U.S. Pat. No. 5,202,185 to Samuelson teaches a method to form an antistatic filament for carpeting comprising a continuous nonconductive sheath of a synthetic thermoplastic fiber-forming polymer surrounding an electrically conductive polymeric core of electrically conductive carbon black dispersed in a thermoplastic synthetic polymer. U.S. Pat. No. 5,290,483 to Kulkarni et al teaches a method to prepare a conductive polymer article comprising an intrinsically conductive polymer and a thermoplastic polymer. U.S. Pat. No. 4,045,949 to Paton et al teaches an electrically conductive filament using conductive carbon black. U.S. Pat. No. 5,520,852 to Ikkala et al and U.S. Pat. No. 5,783,111 to Ikkala et al teach intrinsically conductive polymer compounds where mixing solid conductive particles with thermoplastics is described in the background to the invention.